That is my take as well. Spring 2020 I did a lot of volume (for me) and completed an INSCYD test, my zones:
| Power Zone | low | target | high |
|---|---|---|---|
| Zone2 Coggan/TR/FasCat | 140 | 189 | |
| Zone2 INSCYD | 148 | 175 | 192 |
| FATmax INSCYD | 153 | 170 | 187 |
169W for Coggan classic mid zone2, which coincidentally was virtually the same as INSCYD FATmax.
To be honest I overcooked (upper zone2) some of the longer rides, but overall I tried to keep zone2 rides in the 160s. Lessons learned from this past spring: less is more, fresh is faster (less z2 power is better). Adding in the context of this thread simply reinforces being conservative on zone2 targets while putting in the hours.
Here is a 3 hour zone2 ride this weekend:
Zone2 power is highlighted. I did this by HR, started with temps in low 60s and so power was a bit higher than second half when temps were in mid 80s. Those are 1-min tempo bursts every 5-min. My aerobic endurance is recovering after low-volume month+ due to smoky air (forest fires in NorCal), so it was nice to finish this but it capped off a 10 hour week and I was TIRED yesterday 